This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Ion sources are used across a wide range of applications including basic science research, medical applications, and semiconductor production. In many cases, the performance and reliability of very large, complex, and expensive systems is limited by the performance and reliability of the ion source, which often represents a relatively small part of the total system in terms of size and cost. Thus, advances in ion source technologies can lead to drastic improvements in system performance relatively quickly. However, ion sources are complex devices that often suffer from reliability issues when pushed to high currents, as is often demanded by the rest of the system.
Lifetime and reliability issues are especially troublesome for existing negative ion sources, such as negative hydrogen (H−) ion sources. Nonetheless, negative ion sources are still commonly used across a broad range of applications due to the fact that for many applications, downstream system components require negative rather than positive ions. Conventional negative ion sources may have, for example, a relatively short lifetime of only a few hundred hours. This lifetime decreases even further when operated at full power (e.g., 15 mA). Furthermore, conventional negative ion sources may encounter other problems including high power requirements (15 kW) and high gas load (18-20 sccm) on the downstream vacuum components.
A reliable, long lifetime negative ion source has applications in silicon cleaving for photovoltaic semiconductor applications, isotope production and separation, cyclotron injection systems, and accelerator mass spectrometry. Cyclotrons are widely used across medical and industrial fields. As technology continues to develop, it appears that ion source injectors could become limiting factors with regard to beam current and accelerator performance. There are several technical reasons why it is preferable to inject negative rather than positive ions into cyclotrons, and the low current and short lifetime of existing ion sources will potentially limit the performance of next-generation cyclotrons. Similarly, ion beams are used in a wide range of settings in the semiconductor industry. Better ion sources translate to cheaper, more efficient, and more effective production techniques for circuit components that are the building blocks of all modern IC-based technologies
In another example, the negative ion source may be used in the field of magnetic confinement fusion energy. For decades scientists have sought to develop an energy source based on nuclear fusion reactions, as it could potentially provide an essentially unlimited amount of clean energy with virtually no harmful byproducts. Though fusion energy technologies have advanced immensely over the past several decades, there are still a number of technical challenges that prevented the development of a clean fusion energy reactor. One challenge faced by fusion energy is unreliable high current negative ion sources. Existing negative ion fusion injectors use filaments and/or magnetically coupled plasmas that suffer from many of the deficiencies discussed above. A reliable, long lifetime negative ion source could drastically increase the ion source conversion efficiency, lifetime, reliability, and current output. Developing such a negative ion source could be a major step forward in developing a clean, reliable fusion energy source.
A need exists for improved technology, including technology related to a new type of ion source that can produce high DC current output (up to 10 mA) and have a long lifetime (greater than 1 month).